Both prior and subsequent to 1900, many devices were patented to operate upon wood in various forms, even as logs, and heated by furnaces to form charcoal and gas, some of the gas being referred to as carbureted hydrogen or wood gas. Retorts were also employed in which the wood material was roasted. Some of these devices also contemplated creosote recovery. Since that time, and especially in the past few years during which the "energy crunch" has been in evidence, production of gas and other useful products from many kinds of waste material, including garbage and almost any kind of burnable or fermentable material, has been the subject of wide research and some U.S. patents have been obtained, such as:
U.S. Pat. No. 4,050,970--Brimhall--Sept. 27, 1977 PA1 U.S. Pat. No. 4,057,401--Boblitz--Nov. 8, 1977 PA1 U.S. Pat. No. 4,118,281--Yan--Oct. 3, 1978 PA1 U.S. Pat. No. 4,157,958--Chow--June 12, 1979 PA1 U.S. Pat. No. 3,938,965--Pyle--Feb. 17, 1976 PA1 U.S. Pat. No. 3,950,143--Pyle--Apr. 13, 1976 PA1 U.S. Pat. No. 2,631,930 to Peters, dated Mar. 17, 1963, which discloses carbonizing sawdust by electric heating coils, which keeps sawdust turbulent, ash is removed, and the resulting gas is filtered and collected. PA1 U.S. Pat. No. 3,852,048 to Pyle, dated Dec. 3, 1974, disclosed drying woody waste material which is carbonized to charcoal and fuel gas, is cooled and combined to form an enriched solid charcoal fuel that is pollution-free. PA1 U.S. Pat. No. 3,929,585 to Grimmet, dated Dec. 30, 1975, pertains to mixing waste wood products with inert bed material, such as sand and alumina, to form a fluidizable mixture heated in a bed pyrolyzer to form charcoal, which is separated from the bed material as activated carbon. PA1 U.S. Pat. No. 3,977,947 to Pyle, dated Aug. 31, 1976 relates to forming a hot fluidized bed or previously formed charcoal which is injected into wood waste to form gas and charcoal which are separated and the charcoal is sized for use as fuel. PA1 U.S. Pat. No. 4,028,068 to Kiener, dated June 7, 1977, discloses a process to subject waste material to low temperature carbonization to form gas by exclusion of air which is drawn through a reaction bed of solid carton with fresh air to form high energy combustible gas. PA1 U.S. Pat. No. 4,164,397 to Hunt, dated Aug. 14, 1979, shows converting wood to fuel gas by letting it descend in a bed reactor in which gas is ascending and removed from the top of the reactor, a portion of the gas being recirculated and introduced as reflow gas with air to the combustion zone at the base of the descending bed.
which pertain to recovering or generating gas from garbage and the like.
A recent survey by the Division of Forestry of Florida has revealed that nearly one million tons of wood residue is deposited annually in landfills in that state alone. This conceivably can be salvaged for use as fuel, either directly or converted to useful fuel, such as gas. The farming industry also generates substantial quantities of waste material in the form of corn cobs, fodder, straw, waste vegetation, fence row brush, and the like, much of which is convertible to useful fuel products. The lumber industry also generates vast quantities of waste in the form of chips, sawdust and bark, which similarly can be converted to useful fuel production.
The availability of this type of waste material for development of useful fuel has not gone unnoticed by enterprising individuals and companies, as evidenced by the following U.S. patents, which primarily are directed to the formation of various types of charcoal from wood waste and the like:
Still other efforts have been utilized in the production of useful gas and/or charcoal and evidence of this is found in the following U.S. patents: